Current limiter



Oct. 7 1924.

c. I. HALL CURRENT LIMITER Filed Jan. 25. 1921 Inventor: Che ter- 1.Hall Hi5 Attof'ney Patented Get. 7, 1924'.

UNITED STATES 1,511,015: PATENT oFFic E.

CHESTER I. HALL, 011' FORT WAYNE, INDIANA, ASSIGNOR' TO GENERAL ELECTRICCOIVIPANY, A CORPORATION OF NEW YORK.

CURRENT LIMITER.

Application filed January 25, 1921. Serial No. 439,867.

To all whom it may concern:

Be it known that I, CHESTER I. HALL, a citizen of the United States,residing at Fort Wayne, in the county of Allen, State of Indiana, haveinvented certain new and useful Improvements in Current Limiters, ofwhich the following is a specification.

This invention relates to current limiters, and more particularly tosuch limiters arranged. to interrupt the supply to a load at shortintervals when it reaches a definite maximum value.

Such devices have usually been built in the form of an electromagnet andan armature, the coil of the electromagnet being placed in series withthe load and the armature serving to break the contact wien it isattracted by the elect-romagnet. This causes the deenergization of the.magnet and a corresponding resumption. of the load. If the load stillexceeds the permissible value, the armature is again attracted and theload interrupted. This intermittent flickering continues until the loadis reduced to the proper value. Such devices on the whole have certaindisadvantages. For example, the length of time for which the cont actsare opened may be so short that such loads as heating devices may stillbe operated efficiently, although the current is on intermittently. Itis one of the objects of my invention to render the time interval duringwhich the contacts are open appreciably long so that no form of loadwhatever may be satisfactorily operated while this successiveinterruption of the circuit is taking place, and the customer in orderto get satisfactory service is forced to reduce his load to the valueagreed upon beforehand as the maximum permissible. Another object of myinvention is to construct a device in such a way that an accurateadjustment may be made of the value of the: load at which the contactswill begin to open and close intermittently. Other objects andadvantages will become apparent as the description proceeds.

For a better understanding of my invention reference is to be had to thefollowing specification together with the accompanying drawings, inwhich Fig. 1 is a front view of the electromagnetic current limiterbuilt according to my invention and a schematic wiring diagram showingits mode of Cooperating with the core 13 is a pivoted armature 14 havinga stop 15, preferably of soft yielding material such as felt so as toreduce the noise during operation. The stop 15 acts against the end 16of the armature 14 which is shown as appropriately weighted so as tokeep it away from the pole far-e17 of the core 13. Metallicconductingpieces 18 and 19 are provided and securely fastened to thebase 11, which conducting pieces serve to accommodate binding posts 20and 21, as well as stop 15. The wires 22 and 23 connect these posts tothe load and the source as indicated in Fig. 1. The circuit through thelimiter and load may be traced as follows: wire 23, binding posts 21 and2-1, electromagnet 12, a binding post 25 and from there to a pivotedlever or support 26 which carries a movable contact piece 27 and isappropriately weighted, as for example, by the weight 40. The movablecontact piece 27 coacts withthe stationary contact piece .28 carried bythe metallic member 18 to which the binding post 20 is connected. Frombinding post 20 the wire 22 leads to the load and the source. It is thusevident that the electromagnet 12 is in series with the load and hasitscircuit completed through the movable contact 27 and stationary contact28.

The pivoted support 26 is carried by a plate 29 securely fastened to thebase 11. Furthermore, this support is so formed as shown in Fig. 2 thatis extends directly above the pivoted armature 14 so that when saidarmature 14: is attracted to the pole on face 17 upon energization ofthe electromagnet 12, it strikes against said lever 26, rotating it incounterclockwise direction as viewed in Fi 2 and opening the contactsA1, 27 and 28. The armature must travel an appreciable distance beforeit strikes the lever 26, so that the contacts are opened at a highvelocity. The moment of inertia of Weight 40 is sut'liciently great tocause the pivoted lever 26 to keep on traveling even after the armature14% has reached the end of its travel toward pole face 17. The movementof the support 26 continues until it strikes the stop 30, in thisinstance, formed integral with plate 29. By the time the lever 26returns to the normal position shown in Fig. 2 an appreciable intervalof time has elapsed so that a heating device, for example, could not beefficiently operated. The pivoted lever 26 and the stop 30 are soarranged that there is no danger of this lever staying in the openposition, since the force of gravity always tends to close the contacts.

Under some circumstances it may be advisable to reduce the load to aninappreciable constant value in case a very large load. is attempted tobe taken. For'example, it as much as three or four times the limitingload is reached, it may be advisable to shunt the contact pieces 27 and28 by a comparatively large resistance so that upon opening of thecontacts there is still a path for the current through this resistance,and it the load is suiiiciently great this current is large enough toattract armature 1 1 and hold it in its attracted position. Under suchcircumstances, a small steady load is obtained, until the number or kindof translating devices making up the load is changed nearer to normal.lVhen this happens the armature lat is released and the resistance 31short circuited.

One of the main features of my invention resides in the particular wayin which the core 13 for the electromagnet 12 is supported, so thataccurate adjustment of the air gap between the armature 1e and the poleface 17' may be obtained. F or this purpose I pivot the armature it uponthe core member 13 by means of the pivot pin 32. Adjacent to this pivotpin 32 I provide a pivotal sup port 33 tor the entire core 13. Thispivotal support fastens to the base 11 as may be ascertained by aninspection of Fig. 2. The other end of the core 13 carries a memberprovided with a slot 3 1 through which p asses appropriate fasteningmeans such as a. screw 35, so as to hold the core in its adjustedposition about the pivotal support 33. It is evident that by looseningthe screw 35 and turning the entire core about 33 a pivot, which pivothas an axis perpendicular to the plane of movement of the armature 14,the pole face 12' may be brought nearer to or further from the armature14:. After the proper adjustment is made the fastening means 35 mayagain be tightened. Thus an extremely accurate adjustment of the air gapbetween the armature and core is obtained. The screw is in this instanceshown as threaded. into a member 36 rigidly fastened to the base 11.Furthermore, the slot 34 is ajjiprcpriatcly carried by the bottom plate37 oi? the core between which plate and the top plate 38 the laminationsof the core are compressed. F or compressing these lai'ninations thepivotal support may be used, as well as another fastening means such asthe screw 39.

hile I have shown in the accompanying drawings but one embodiment of myinvention, I do not wish to be limited thereto but aim to embrace in theappended claims all modifications falling tairly within the scope of myinvention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is

1. In a current limiter having contacts, an electromagnet, acore forsaid electromagnet, an armature for operating the contacts, a pivotalsupport for said core, a pivot carried by said core for the armatureadjacent the pivotal support for the core, said parts being so arrangedthat the adjustment of the core about its pivot changes the deenergizedposition of the armature with respect to the core, and means foradjusting the angular position oi said core about its pivotal support.

2. In a current limiter having contacts, an electromagnet, a core forsaid electromagnet, an armature for operating the contacts, a pivot forsaid armature carried by said core, a base for independently supportingthe contacts and electromagnet, a pivotal support extending from thebase through the core adjacent the pivot for the armature, said corehaving a slot. and fastening means passing through said slot, wherebysaid core may be angularly adjusted about its pivotal support.

In witness whereof, I have hereunto set my hand this Zeth day ofJanuary, 1921.

CHESTER I. HALL.

